Compost Under Vines Trial Results

On Friday 28th April, our Regional Landcare Facilitator Karen Thomas, alongside Westernport Catchment Landcare Network, ran the final compost under vine results day at Balnarring on the Mornington Peninsula.

This three year project has been trialling fine compost and compost mulch from urban green waste (in comparison with a control) in a 100cm wide strip under the vines at four vineyards on the Mornington Peninsula. The final year of the trial is now complete and interesting results have been recorded and observed.

At the event a range of speakers discussed the results:

  • Declan McDonald: soil health benefits from applying the compost treatments under vine
  • Erika Winter: winegrape canopy and winegrape chemistry assessments
  • Joe Vaughan: observations after using compost under vine for a number of years at 100Hunts Vineyard

Advantages

The main advantages of the mulch treatments that were observed related to:

  • a lower soil bulk density
  • a more moderated day night soil temperature fluctuation
  • a reduction of water use
  • increases in soil microbial biomass.

Improvements to soil condition

The results showed that improvement in soil condition leads to better plant health and reduced water stress. As an example, one vineyard recorded irrigation savings of 20% in summer 2016 (dry year) where the control row used 2ml/ha and the fine compost block used 1.6ml/ha from November to March. This amounted to savings of 416,000l/ha.

In 2017, a wetter year, they still had irrigation savings of 12%, where the control row used 1.3ml/ha and the fine compost used 1.1ml/ha.

Early ripening

In 2017, winegrape quality traits were measured by Vintessential Laboratories. Earlier ripening berries were observed in the rows with compost or compost mulch in three out of four vineyards. Riper grapes that are ready before the autumn rains may ​increase disease pressure.

The soil under the coarse mulch was drier and warmer in summer than that of the other rows and this may be a contributing factor for earlier ripening. Anthocyanins were higher per mg berry in grapes of the mulch treatments compared to those from the controls.

Other observations

Other benefits to applying compost under vine were empirically observed:

  • Healthier canopies with less senescence at vera​is​on
  • More fibrous roots in the top 300mm soil profile
  • Following harvest, the vine leaves held on longer with compost than the control.

Variances and future data collection

There were some statistically significant differences between treatments due to very different rainfall conditions in all three years. Some clear trends which were evident in a dry year could not be observed after the very wet spring in 2016. With climate variability to be expected to increase, several seasons of observation would be desirable to provide more concrete results.

To further substantiate all of the trial data, continuation of the measurements of soil moisture, soil temperature, bulk density and soil biological activity as well as bunchzone temperature, canopy characterisations like leaf health, vine balance and ratio of young to active leaves and winegrape chemistry needs to occur for at least two more years.

 

If have have any questions regarding the trial, please contact Karen Thomas on 03 8781 7945 or karen.thomas@ppwcma.vic.gov.au.

Download Declan McDonald’s presentation – Compost under vines summary (PDF – 68KB)

Download Declan McDonald’s presentation – Compost use in vineyards (PDF – 264KB)

Download grape analysis report (PDF – 51.6KB)